Washingtonian reports today that chef Barton Seaver has left his post at Hook. Seaver, formerly of Jaleo and Café Saint-Ex/Bar Pilar, has been with Hook since it opened in March 2007. Seaver has become a golden boy of sorts in the D.C.-area for his dedicated advocacy of sustainable seafood, and has been honored by the Blue Ocean Institute for his commitment to oceanic sustainability. It’s not surprising then that Seaver’s post-Hook plans include ambitions to…